The present disclosure relates to a robot arm, a method of estimating an amount of iron powder contained in a lubricant of a connecting part of a robot arm, and an abnormality sign determination system.
In a common robot arm, a motor is connected to an arm with a connecting part interposed there between. The connecting part includes a lubricant such as grease inside the connecting part. An amount of the iron powder in the lubricant increases with an operation of the robot arm, and the consistency of the lubricant decreases. As a result, the lubricant deteriorates, causing an abnormality in the connecting part and eventually in the robot arm.
Commonly, for example, an abnormality sign in a robot arm is diagnosed (determined) by detecting an amount of iron powder in a lubricant using a lubricant deterioration detecting apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2007-248211. In the lubricant deterioration detecting apparatus of Japanese Unexamined Patent Application Publication No. 2007-248211, the lubricant is irradiated with light from a light emitting unit, and a light receiving unit receives the light transmitted through the lubricant to calculate light transmittance of the lubricant in order to detect the amount of iron powder in the lubricant.